Tests and diagnosisBy Mayo Clinic staff
Diagnosing Rett syndrome involves careful observation of your child's growth and development and answering questions about her or his medical and family history.
Your child may also have certain tests to identify conditions that can cause some of the same symptoms as Rett syndrome. Some of these conditions include:
- Other genetic disorders
- Cerebral palsy
- Hearing or vision problems
- Disorders that cause the brain or body to break down (degeneration disorders)
- Brain disorders caused by trauma or infection
- Prenatal brain damage
What tests your child needs depends on particular signs and symptoms. Tests may include:
- Blood tests
- Urine tests
- Tests to measure the speed of impulses through a nerve (nerve conduction studies)
- Imaging tests such as magnetic resonance imaging (MRI) or computerized tomography (CT) scans
- Hearing tests
- Eye and vision exams
- Brain activity tests (electroencephalograms, also called EEGs)
Your doctor may recommend a genetic test (DNA analysis) to confirm a diagnosis of Rett syndrome. The test requires drawing a small amount of blood from a vein in your child's arm. The blood is then sent to a lab, where technicians examine your child's DNA for abnormalities and clues as to the cause and severity of your child's disorder.
If your child's doctor still suspects Rett syndrome after considering other possibilities, he or she will use specific guidelines for diagnosis.
Official diagnostic criteria
Doctors use different criteria to diagnose Rett syndrome, but all include similar signs and symptoms. One common set of criteria is spelled out in the Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association.
The criteria required for a diagnosis of Rett syndrome include:
- Apparently normal development for the first five months after birth
- Normal head circumference at birth, followed by a slowing of the rate of head growth between the ages of 5 months and 4 years
- Severely reduced language skills
- Loss of hand skills and development of repetitive hand movements between the ages of 5 months and 30 months
- Loss of interaction with others (though this often improves later)
- An unsteady walk or poorly controlled torso movements
- Severely impaired ability to communicate and move normally
In addition to these core symptoms, children with Rett syndrome may have other signs and symptoms. In certain cases, children may have many of the signs and symptoms of Rett syndrome but not show all of them. This is known as variant or atypical Rett syndrome.
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